1. Field of the Invention
This invention relates to a surgical instrument, in general, and to a manually-powered surgical stapling instrument for stapling together disunited segements of the external skin or internal fascia of a patient, in particular.
2. Description of the Prior Art
In U.S. Pat. No. 3,643,851, assigned to the present assignee and entitled SKIN STAPLER, there is disclosed a gas powered surgical stapler, employing a staple-carrying cartridge, for joining the disunited skin of a patient. Later developments of the gas-powered stapler and cartridges for applying surgical staples to external skin and internal fascia are disclosed in U.S. Pat. No. 3,662,939, assigned to the present assignee and entitled SURGICAL STAPLER FOR SKIN AND FASCIA.
A manually powered surgical instrument adapted to accept staple-carrying cartridges of the type disclosed in the above commonly assigned patents is disclosed in U.S. Pat. No. Re. 28,932, assigned to the present assignee and entitled SURGICAL STAPLING INSTRUMENT.
Recently, staple-carrying cartridges have been designed which eliminate the requirement for the complex gearing once needed in the powering of the surgical instrument. With these cartridges, the output shaft of the powering instrument need only have rectilinear thrust capabilities. The staples are advanced by means designed into the cartridges themselves. In commonly assigned U.S. Pat. No. 3,618,842 entitled SURGICAL STAPLING CARTRIDGE WITH CYLINDRICAL DRIVING CAMS, the advancing pusher, integral with the cartridge, rotates a pair of staple-driving screws by means of cams formed in the rear portions of the screws. In commonly assigned U.S. Pat. No. 3,638,847 entitled RACHET DRIVEN CARTRIDGE FOR SURGICAL INSTRUMENTS, the staples are driven forward by the interaction of pairs of opposing rachet teeth integral with the cartridge. In commonly assigned U.S. Pat. No. 3,650,453 entitled STAPLE CARTRIDGE WITH DRIVE BELT, the staples are driven forward by a flexible drive belt. Finally, in commonly assigned U.S. Pat. No. 3,717,294 entitled CARTRIDGE AND POWERING INSTRUMENT FOR STAPLING SKIN AND FASCIA, a flexible toothed belt is moveably housed in a main body. Staples are guided and advanced by association with spaced teeth of the flexible belt. The cartridge is equipped with an anvil integral with the main body and with a pusher which serves the functions of advancing the staples and singly ejecting and forming the same.
In U.S. Pat. No. 3,949,924, assigned to the present assignee and entitled SURGICAL STAPLING INSTRUMENT, there is disclosed a manually powered surgical instrument for stapling together disunited segments of the external skin or internal fascia of a patient.
The surgical stapling instrument of U.S. Pat. No. 3,949,924 generally comprises a main body portion having a nose portion rotatably mounted therein and adapted to receive and mount a staple-carrying cartridge. The nose portion of the stapler has the drive means for advancing and forming the staples of the cartridge mounted thereto. A pusher-activating means for driving the pusher element of the staple-carrying cartridge to advance, eject and form the staples around the anvil means of the cartridge comprises a thrust bar slidably mounted for reciprocative movement in the stapler. The thrust bar is adapted to move with a collar element slidably mounted in the stapler. A trigger means comprises a handle which is pivotally mounted on the main body portion of the stapler and has means for engaging the collar element so that the thrust bar is moved forward by squeezing the trigger to advance the staples.
An impact mechanism mounted in the stapler includes an impact spring which is loaded by squeezing the trigger and a plunger acted upon by the impact spring which is released and strikes the thrust bar when the staples are ready for ejection and forming. A return spring attached to the trigger and to the main body portion of the stapler functions to return the thrust bar to its initial position after the thrust stroke of the bar has been completed. Means are also provided for preventing more than one staple from being placed in the ready position of the staple-carrying cartridge during the stapling operation. This means comprises a clutch means which prevents the return of the thrust bar to its initial position until it has completed a full stroke, thereby ejecting a staple from the staple-carrying cartridge.